1. Field of the Invention
This invention relates to a hot melt applicator that stores multiple blocks of solid adhesive to be dispensed.
2. Description of the Related Art
Many types of hot melt applicators are adapted for hand-held use so that the molten adhesive can be conveniently maneuvered and placed at a selected location on a workpiece. Conventionally, smaller hand-held hot melt applicators have a manually operated feeding mechanism for pushing a block of solid hot melt material toward a melting chamber. Some of the larger hot melt applicators have an air-operated piston and cylinder assembly for pushing the blocks of hot melt material toward the melting chamber with less operator effort. An improved manually operated feeding mechanism for a hot melt applicator is described in U.S. Pat. No. 4,951,846. U.S. Pat. No. 4,457,457 shows a larger applicator having an air-operated piston and cylinder feeding mechanism.
Some hot melt applicators are provided with a storage receptacle for holding extra blocks of solid hot melt material, so that there is less interruption of the work operation after the first block of material is melted and dispensed. The applicator described in U.S. Pat. No. 4,457,457 has a storage receptacle that is located between and above the melting chamber and the cylinder of the piston and cylinder assembly. As the piston of the applicator in U.S. Pat. No. 4,457,457 is retracted, the next block of solid hot melt material descends through a bottom opening of the receptacle to a position in front of the piston, whereupon the piston can be advanced to push the descended block toward the melting chamber. The piston during advancement also blocks the bottom opening of the receptacle so that the remaining blocks of material in the receptacle are retained in the latter until such time as the piston has completed its advancement and is then withdrawn to its starting position to allow the next block to descend through the opening.
However, there is a continuing desire to reduce the overall size of hot melt applicators as much as feasible in order to improve the maneuverability of the applicator as well as the operator's vision of the work operation, especially in instances where the molten adhesive must be placed at a precise location on the workpiece. While the applicator shown in U.S. Pat. No. 4,457,457 has provided satisfactory performance, the piston and cylinder assembly extends behind the storage receptacle a significant distance which is somewhat greater than the length of the blocks to be dispensed, and additional space is also consumed by the pressurized air connection at the rearmost end of the cylinder. The piston and cylinder assembly may also inhibit rearward movement of the block as the front portion of the block expands in the melting chamber after a dispensing operation, possibly causing unwanted molten adhesive to drip from the applicator's nozzle.